The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

I'm not so much worried about emissions, they're non-existent where I live, I just want to keep the CEL gremlins from harassing me until the ECU gets it's reprogram

Update: Just talked to NGK rep and he had me go to https://ngksparkplugs.com/en/part-finder and use their part finder. It does have listings for Federal and CA emissions.
2000 4.0l 5spd
Federal emissions (Only 2 sensors)
23122 upstream
23099 downstream

Did that work out?

I'm dealing with the same. Unless I'm mistaken, my 2000 4.0 only has two underneath, with plugs covering the two under the hood. Also, no O2 (CA) fuse.

According to NGKs site this should be 23122 and 23099, which is contradicting.
 
Did that work out?

I'm dealing with the same. Unless I'm mistaken, my 2000 4.0 only has two underneath, with plugs covering the two under the hood. Also, no O2 (CA) fuse.

According to NGKs site this should be 23122 and 23099, which is contradicting.
I haven't gotten around to replacing my O2 sensors yet, since I replaced the spark plugs I haven't got another code.
I'm not quite sure what "plugs" you're referring to under the hood. As to the difference between Fed and CA emissions on the 2000 model 4.0l, the CA emissions has 2 "pre-cats" directly below the exhaust manifold with an 02 sensor just after each of those. The Federal emissions model has the same style exhaust manifold but no pre-cats.
If you in fact have the Federal Emissions then the 2 NTK numbers you stated are correct.

2000 Federal Emissions The 2 sensors are located under the body tub, one in front of the cat before the flange, and the other after the cat (not pictured here)
1581450599982.png
2000 CA Emissions The 2 up stream sensors are in the exhaust manifold before the pre-cats and the 2 down stream are after the pre cats.
1581450644042.png
 
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I haven't gotten around to replacing my O2 sensors yet, since I replaced the spark plugs I haven't got another code.
I'm not quite sure what "plugs" you're referring to under the hood. As to the difference between Fed and CA emissions on the 2000 model 4.0l, the CA emissions has 2 "pre-cats" directly below the exhaust manifold with an 02 sensor just after each of those. The Federal emissions model has the same style exhaust manifold but no pre-cats.
If you in fact have the Federal Emissions then the 2 NTK numbers you stated are correct.

2000 Federal Emissions The 2 sensors are located under the body tub, one in front of the cat before the flange, and the other after the cat (not pictured here)
View attachment 139629
2000 CA Emissions The 2 up stream sensors are directly below the pre-cats and the 2 down stream are before and after the main cat.
View attachment 139630
I haven't gotten around to replacing my O2 sensors yet, since I replaced the spark plugs I haven't got another code.
I'm not quite sure what "plugs" you're referring to under the hood. As to the difference between Fed and CA emissions on the 2000 model 4.0l, the CA emissions has 2 "pre-cats" directly below the exhaust manifold with an 02 sensor just after each of those. The Federal emissions model has the same style exhaust manifold but no pre-cats.
If you in fact have the Federal Emissions then the 2 NTK numbers you stated are correct.

2000 Federal Emissions The 2 sensors are located under the body tub, one in front of the cat before the flange, and the other after the cat (not pictured here)
View attachment 139629
2000 CA Emissions The 2 up stream sensors are directly below the pre-cats and the 2 down stream are before and after the main cat.
View attachment 139630

Understood. I appreciate the explanation, that is what I have then. I was confusing the hex head on the bottom of the manifold where the original illustration is showing a sensor.

Hope the code stays at bay for you.
 
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@Chris, not sure what’s going on here. I bought the B2S1 NTK linked to in original post for a 2005 TJ. Part No. 23160. It is the same one in the NGK website as well. But the harness connects slightly different. See pics below:

Note on the left side of each connector the c channel is lower in the original than on the replacement. Because if this they won’t slide together
38C21B06-0F45-4862-B2A2-DF5C3D728073.jpeg

Image below is from the NGK website. It’s just like the one I ordered above, but won’t fit.

7327F0FC-8E76-4C7C-9054-7C54584AB50A.jpg
 
@Chris, not sure what’s going on here. I bought the B2S1 NTK linked to in original post for a 2005 TJ. Part No. 23160. It is the same one in the NGK website as well. But the harness connects slightly different. See pics below:

Note on the left side of each connector the c channel is lower in the original than on the replacement. Because if this they won’t slide together
View attachment 140438
Image below is from the NGK website. It’s just like the one I ordered above, but won’t fit.

View attachment 140439

Wow, that's really, really odd. I never had this issue when I did mine.

While I don't know why this is, you know what I would do? Take the connector from your old one and reuse it on the new one.

If you have these types of wiring tools, it's a piece of cake to swap connectors:

https://www.amazon.com/dp/B082FDGVD9/?tag=wranglerorg-20
 
Wow, that's really, really odd. I never had this issue when I did mine.

While I don't know why this is, you know what I would do? Take the connector from your old one and reuse it on the new one.

If you have these types of wiring tools, it's a piece of cake to swap connectors:

https://www.amazon.com/dp/B082FDGVD9/?tag=wranglerorg-20
I know, you’ve had ‘05’s. This is a mystery to me. It made me think either the part no was wrong or something happened in the OEM manufacturing of my rig (which would be so odd).
I may look further into this before cutting the wires and using the old harness
 
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I know, you’ve had ‘05’s. This is a mystery to me. It made me think either the part no was wrong or something happened in the OEM manufacturing of my rig (which would be so odd).
I may look further into this before cutting the wires and using the old harness

No need to cut the wires if you use those tools I posted the link to.

But yes, if you look into it further, I'd be curious to hear what you find.
 
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What are Bank 1, Bank 2, etc.?
Since this question pops up from time-to-time, here's an easy to follow diagram that illustrates what they mean when your OBDII code scanner (or manual) tells you something like "O2 sensor, Bank 1, Sensor 2":

View attachment 12208


What does upstream and downstream mean?
Simple, upstream means the O2 sensor is "upstream" of the catalytic convertors, meaning before the catalytic convertors. Downstream means the O2 sensor is "downstream" of the catalytic convertors, meaning after the catalytic convertors.


What brand of O2 sensors should I use for replacements?
Pay close attention to this one so you can do it once and do it right! The Jeep Wrangler TJ is extremely sensitive to all oxygen sensors other than NGK / NTK. Bosch O2 sensors and all the others (including the crappy Chinese brands you'll buy at your local auto part store) are very well documented as not working properly with our TJs. In other words, you plug them in and you assume all is well, until you notice your check engine light isn't going away. This is almost always due to the fact that you didn't use an NGK / NTK replacement O2 sensor.


Okay, so why don't other sensors (i.e. Bosch) work on our Jeeps?
Glad you asked! Check out this video for a detailed explanation of why other brands of O2 sensors don't work on our TJs:



So which O2 sensors do I need?
I'm going to break down which sensors you need based off what year your TJ is. The part numbers (and information) below were taken directly from the NGK website, so you can assure it is 100% accurate (even double checked each individual year and model before writing this thread).


4 Cylinder Engines
1997-2000
NGK #23506 - Bank 1, Sensor 1 (Upstream)​
NGK #23151 - Bank 1, Sensor 1 (Upstream) (1998 ONLY)​
NGK #23099 - Bank 1, Sensor 2 (Downstream)​
2001-2004
NGK #23138 - Bank 1, Sensor 1 (Upstream)​
NGK #23141 - Bank 1, Sensor 2 (Downstream)​
2005-2006
NGK #23159 - Bank 1, Sensor 1 (Upstream)​
NGK #23159 - Bank 1, Sensor 2 (Downstream)​
6 Cylinder Engines
1997-1999
NGK #23151 - Bank 1, Sensor 1 (Upstream)​
NGK #23099 - Bank 1, Sensor 2 (Downstream)​
2000
NGK #23122 - Bank 1, Sensor 1 (Upstream)​
NGK #23506 - Bank 2, Sensor 1 (Upstream)​
NGK #23099 - Bank 1, Sensor 2 (Downstream)​
NGK #23099 - Bank 2, Sensor 2 (Downstream)​
2001-2003
NGK #23139 - Bank 1, Sensor 1 (Upstream)​
NGK #23138 - Bank 2, Sensor 1 (Upstream)​
NGK #23142 - Bank 1, Sensor 2 (Downstream)​
NGK #23141 - Bank 2, Sensor 2 (Downstream)​
2004
NGK #23137 - Bank 1, Sensor 1 (Upstream)​
NGK #23135 - Bank 2, Sensor 1 (Upstream)​
NGK #23132 - Bank 1, Sensor 2 (Downstream)​
NGK #23531 - Bank 2, Sensor 2 (Downstream)​
2005-2006
NGK #23018 - Bank 1, Sensor 1 (Upstream)​
NGK #23160 - Bank 2, Sensor 1 (Upstream)​
NGK #23159 - Bank 1, Sensor 2 (Downstream)​
NGK #23158 - Bank 2, Sensor 2 (Downstream)​
Misc Installation Notes
When installing new O2 sensors, be certain to use some anti-seize on the threads of the new O2 sensors! This is important, and will save you a huge headache should you ever need to remove them in the future.

In addition, a O2 sensor socket will greatly aide in the installation and removal of O2 sensors. I recommend this one.

is there any particular reason the amazon links for the 2004 4.0 sensors are SIGNIFICANTLY cheaper than ordering from Napa or Autozone? Just wanna make sure I’m getting legit parts
 
is there any particular reason the amazon links for the 2004 4.0 sensors are SIGNIFICANTLY cheaper than ordering from Napa or Autozone? Just wanna make sure I’m getting legit parts

Yes, because amazon is almost always cheaper than those places. The sensors are real. Go read through this thread it in doubt. Everyone gets them from amazon 👍
 
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Newbie on this forum and I have a ridiculous problem...I cannot get the electrical connector to come apart on my O2 sensors! The downstream one appears to be original on my 2002 SE 2.5 and the red flag portion was brittle and snapped with little provocation. I can see the latch move, but no amount of wiggling would get them to separate. If there’s a trick, I haven’t figured it out yet.
I didn’t need to replace the sensor...the Jeep runs great. I am replacing the clutch and the manual said “remove parts of the exhaust as necessary”. I figured I would at least need to pull the cat off, but now I am not sure that it will be required. So that’s how I started futzing around with the O2 sensor. I have the socket and got it out with little problem (there was enough slack in the cable to remove the sensor by allowing the wires to twist gently) If I don’t need to pull the cat, then I will just put the sensor back...although it wouldn’t hurt to go ahead and change them both out now that I’m partway there...if I can only get the bloody connectors off!
Approaching 70, I no longer have the strength of my youth, but I have wrenched for years and have a lift, high lift transmission jacks and a well equipped shop.
I am embarrassed to be flummoxed by two little electrical connectors...

Kim
 
Newbie on this forum and I have a ridiculous problem...I cannot get the electrical connector to come apart on my O2 sensors! The downstream one appears to be original on my 2002 SE 2.5 and the red flag portion was brittle and snapped with little provocation. I can see the latch move, but no amount of wiggling would get them to separate. If there’s a trick, I haven’t figured it out yet.
I didn’t need to replace the sensor...the Jeep runs great. I am replacing the clutch and the manual said “remove parts of the exhaust as necessary”. I figured I would at least need to pull the cat off, but now I am not sure that it will be required. So that’s how I started futzing around with the O2 sensor. I have the socket and got it out with little problem (there was enough slack in the cable to remove the sensor by allowing the wires to twist gently) If I don’t need to pull the cat, then I will just put the sensor back...although it wouldn’t hurt to go ahead and change them both out now that I’m partway there...if I can only get the bloody connectors off!
Approaching 70, I no longer have the strength of my youth, but I have wrenched for years and have a lift, high lift transmission jacks and a well equipped shop.
I am embarrassed to be flummoxed by two little electrical connectors...

Kim
Have you tried using a little penetrating fluid?
 
Have you tried using a little penetrating fluid?
Actually, yes. I may break out some vice-grips to get a better grip on the two halves, but I suspect it may be a little brittle due to age and I am trying to avoid KOing the thing. I feel it's silly, as I have worked on stuff for decades, and have had no problems with other emission control connections, but these little guys gave me fits.

I appreciate any and all suggestions!
Kim
 
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Hey. Struggling to get downstream rear sensor out. 2001 4.0 116k. Throwing P0158. I have the new sensors but the old one won’t budge. I’ve got both inline and offset O2 sockets. Tried heat (propane) and days of PB blaster. At this point the sensor is rounded off so I can try about anything, but my question is this:

has anybody disconnected the front driveshaft to have better access to the sensor? I feel like I could move it out of the way and get better leverage around the sensor. Or am I asking for trouble? Should I go get a MAP torch?

B156E3EF-4BC2-44E0-972F-8989E0DDB955.jpeg

CBD85057-CA39-4A02-990E-BB41C021F6DC.jpeg



Thanks in advance
FC7DA803-9630-4DF2-956B-64607F7ED2A7.jpeg
 
Is it safe to keep driving with P0138 ? I have ordered the part I need but with whats currently going on its probably going to take a month to arrive.
 
I replaced cats and all 4 o2 sensors. Had a new muffler put on as well (deleted 3rd cat)
Jeep ran fine no codes.
Since I have plenty of down time , having to "work from home" and Alabama being on lock down, I decided to go ahead and replace my heater core , take the 4"lift out and install the 2" lift and be shocks. I also installed the ZJ steering and RC front track bar.
When it came time to fire the jeep up and top off the coolant after the heater core change I got a code P0058.
(P0058 is heated oxygen sensor heater control circuit high voltage bank 2 sensor 2). All sensors are new, I have checked wiring no pinched or frayed wiring, I checked the connection no moisture or anything. I tried clearing the code by removing the negative side of the battery without success. Any idea to why I am all the sudden throwing the P0058 CODE ?
 
attention 6 cylinders 2001-2003 with only 2 sensors:
My 01 Tj Sahara 4L 6Cylinder RWD export version doesnt follow the california emission diagram and it has 2 sensors, one just before and one after the catalytic convertors.
I used:
#23139 Bank 1 Sensor 1 (Upstream)
#23141 Bank 2 Sensor 2 (dowstream)
It works fine.
(The socket is different for each sensor: #23138 and #23142 didnt fit.)
To cut a long story short, i get a CEL about the upstream O2 sensor. Since the jeep, which is a 2002 Sport with the 4.0L, is an export model (Europe), it has only 2 O2 sensors. One before the cat (upstream) and one after the cat (downstream). I pulled out the problematic upstream sensor and its part number is 56041887AA. Since the OEM is around 175$, I am trying to find the NTK equivalent but without luck. My question is: shall i go for the NTK 23151 (of the 97-99 yr model stated in the beginning of the thread) or is there another NTK part number for a direct replacement to 56041887AA? Any help will be appreciated!
Update: After Googling on NTK 23151 and comparing it to the Upstream O2 sensor that i had (Mopar 56041887AA), i found out that the connectors are incompatible (NTK 23151 being a round one). So, i sent a message to NGK requesting their part number for Mopar's 56041887AA. They suggested NTK 23138, which is actually the Upstream sensor of the 2.5L. I ordered it and it looked almost like the Mopar one that i had. The only difference was that the slot on one side of the connector was not lining up correctly (photo included). Then i trimmed the plastic tab that didn't align (i thought that this would be easier than cutting and replacing the connector with the old one). Plugged it in, removed the positive battery pole for about 10 minutes to clear the error codes and voila, no more error codes. Been driving the Jeep for some time now with no problems. Therefore, for an EU spec 2002 TJ Sport with the 4.0L and only 2 O2 sensors, Mopar's 56041887AA has the NTK 23138 (with minor trimming) as an equivalent. So it triggers the following questions: do these 2 sensors only differ in their connectors? Are all upstream sensors for Jeeps the same and only differ in their connectors? And, if so, why do they change the connectors, creating more part numbers and more mess?

Good afternoon everyone from Spain. First of all, I wish you good health to everyone. This is my first post in this forum and I hope not be complicated in my question. I quote three posts that I think are contradictory. Nobody in Spain solves the question about which are the NTK references for a TJ 4.0 from 2001 that only has two oxygen sensors.
Sorry for my poor writing. Thank you so much.